Telephone signal circuit



Nov. 10, 1936. T I LER 2,060,585

TELEPHONE SIGNAL CIRCUIT I Filed Sept. 6, .1935

[ al cl 0 A TT ORA/E V Patented Nov. 10, 1936 UNITED STATES PATENT OFFICE TELEPHONE SIGNAL CIRCUIT Application September 7 Claims.

This invention relates to telephone systems and has for its object to give improved indication of the functioning of such systems.

In telephone ofiices employing call distribution, it is customary to direct only one call to an operator at a time, other calls being held in abeyance until an operator is idle. Heretofore, it has been customary to employ 2. calls waiting signal arrangement indicating that certain fixed numbers of calls are waiting. This signal has the drawback that a given number of waiting calls may be negligible when a large force of operators is on duty and mean a serious delay with a small force.

In accordance with. the present invention, a ca1ls waiting signal is provided which varies in sensitivity in accordance with the number of operators working.

More specifically, the signal operating means is connected to a point, the potential of which is varied according to the number of operators positions in service and the number of calls stored. To this end, each position as it is occupied c'onnects battery through a resistance to this point while as each call is stored, the link connects ground through a resistance to the same point. The signal will be arranged to operate at such a potential as to give the desired indication.

The invention will be more clearly understood from a consideration of the following description in connection with the attached drawing which shows the calls waiting signal circuit together with parts of several link circuits and parts of several operators positions.

This calls waiting signal is adapted for use in connection with such operators equipment as shown in the patent of J. F. Dahl, 2,020,458, granted Nov. 12, 1935, to which reference is made for complete operation of the position and link circuits. In the system of this application, when a call reaches the ofiice at which the operators equipment is located, an idle link circuit is seized and this link hunts for the line over which the call is received. At the same time the link starts hunting for an idle operators position. When the incoming line is found, the link sequence switch advances to position 3 and remains in this position until the operators position has been found. While the link sequence switch remains in position 3 the call is waiting for attention and the link sequence switch connects ground through a resistance to the calls waiting signal circuit.

When the sequence switch of one of the link circuits, indicated in the drawing at A, B, C, and

6, 1935, Serial No. 39,469

D, for example link A, arrives in position 3, it connects ground over cam |2 through resistance l3 to conductor 40 leading to the calls waiting signal circuit, where it extends over the ring contact of jack M to point 6 and thence over the tip con- 5 tact of jack I5, upper windings of polarized relay Hi, ring contact of jack |5 to battery through resistance llr Normally relay I6 is polarized by a circuit from battery through resistance I8, auxiliary contact of jack i5, lower windings of relay 10 iii to ground at the normal contact of relay l9. As thus biased, relay I 6 does not close its contact until two link circuits connect ground to its upper windings. When this occurs, ground is connected in shunt of battery through resistance 20 to the 15 winding of relay 2|, operating that relay. Relay 2| lights green lamps 22, 23 and 24 in the calls waiting signals 43, 44 and 45 respectively at the operators positions to indicate that calls are waitmg.

At the operators desk, the positions are occupied when the operator inserts her headset plug into the position jack. When an operator inserts her plug I into the jack 2 of position II a circuit is completed from ground through the right winding of repeating coil 3, tips of jack 2 and plug including the operators transmitter, winding of relay 4 and battery. Relay t marks the position as occupied and ready to receive calls. It also closes a circuit over its outer upper front contact from battery through resistance 5, to the outer left armature of relay 2| in the calls waiting signal circuit. In a similar manner, relay 1 of position III connects battery through resistance 8 to the armature of relay 2|. Position I is shown as one served by more than one calls waiting signal circuit as might be desirable in large ofiices. Therefore relay 8, connects ground over its outer upper contact to the winding, of relay l0 which connects battery through resistance H to the armature of relay 2| and. connects battery through similar resistances to relay 2| of other calls waiting signal circuits.

Until at least two calls are waiting, these position batteries are ineffective. However, when relay 2| operates, it connects these batteries over its outer left contact, auxiliary contact of jack M in parallel with battery through resistance l1 and over the ring contact of jack Hi, the upper windings of relay I6 and the tip contact of jack l5 to point 6, to which point the voltmeter relay 22, which controls the other signal lamps, is connected as will appear immediately.

voltmeter relay 22 normally holds its lower contact closed. Therefore when relay 2| operates a circuit is closed from ground at the inner right contact of relay 2| winding of relay 23, lower contact of relay 22, resistance 24 and battery. Relay 23 operates, closing a circuit from ground at the outer right contact of relay 2|, front contact of relay 23, winding of relay 25 and battery. Relay 25 causes the operation of relay 26 and relay 2'! in turn, relay 2! locking under the control of relay 2! Relay 21 connects the winding of voltmeter relay 22 to point 6, in parallel with the position resistances.

voltmeter relay 22 is adjusted to open its lower contact at one predetermined potential and to close its upper contact at a second higher potential.

Since the positive pole of battery is connected to ground, as additional positions are put into service, the potential of point 5 decreases, while as additional link circuits come into waiting position the potential of point 6 is raised. With a fixed number of positions in service, the opening of the lower contact of relay 22 and the closure of its upper contact indicate that certain definite numbers of calls are waiting. However, where the number of positions varies, the number of calls waiting indicated by these conditions also varies, but the proportional indication remains about the same.

When the potential of point 6 becomes high enough to cause relay 22 to open its lower contact relay 23 releases in turn releasing relays 25 and 26, which are slow to release. If the condition persists until relay 26 closes its back contact, a circuit is closed from ground at the outer right contact of relay 2|, back contact of relay 26, inner lower front contact of relay 21 to the winding of relay 28 and battery. Relay 28 lights white lamps 29, 30, 3|, etc. in this calls waiting signals at the positions, indicating that there are a considerable number of calls waiting. A circult is also closed in parallel with relay 28 over the outer lower contact of relay 27 to interrupter 32. Interrupter 32 operates relays 33 and 34, followed by buzzer 36 if the condition continues a half minute or more. The buzzer can be silenced by operating key 35.

If the number of waiting calls drops, reducing the voltage of point 6, relay 22 will reclose its lower contact, reoperating relays 23, 25, 26 and 2'! releasing relay 28 and extinguishing the white lamps.

If the number of calls waiting increases until the potential of point 6 is sufficient to cause relay 22 to close its upper contact, relay 3! operates, in turn operating relay 19 which opens the polarizing circuit for relay l6 and closes a circuit for relay 39. Relay 39 lights red lamps 40, M and 42 and also operates buzzer 36. The lamps are immediately extinguished when relay 22 opens its upper contact and releases relays l9 and 39.

The resistances selected for the circuit forming the basis of the present disclosure are 426 ohms for resistance 11, 1260 ohms for resistances 5 and B, and 4800 for resistance l3. Resistance II depends on the number of signal circuits to which the position is common, being a corresponding multiple of the single position resistance. These resistances and the adjustment of the voltmeter relay are made such as to give the white lamp signal whenever the number of calls waiting may delay the time of answer over two seconds and give the red lamp signal when the number of calls waiting exceeds the number required for the white lamp signal by approximately eighty per cent. The actual number of waiting calls necessary to give either signal will vary with the number of positions occupied.

What is claimed is:

1. In a telephone system, a plurality of operators positions, a plurality of link circuits having access to said positions, means to seize said link circuits, a calls Waiting signal controlled by said link circuits when seized, and means to vary the sensitivity of said signal in accordance with the number of said operators positions.

2. In a telephone system, a plurality of operators positions, a plurality of link circuits having access to said positions, means to seize said link circuits, a calls waiting signal controlled by said link circuits when seized, means to vary the sensitivity of said signal in accordance with the number of said operators positions, and means to indicate the operation of said signal at each of said operators positions.

3. In a telephone system, a plurality of operators positions, a plurality of link circuits having access to said positions, means to seize said link circuits, a calls waiting signal at each operators position, and means to operate said signal to indicate when the relation between the number of calls waiting and the number of operators positions in service reaches a predetermined ratio.

4. In a telephone system, a plurality of operators positions, a plurality of link circuits having access to said positions, means to seize said link circuits, a calls waiting signal at each operators position, and means to variably operate said signal to indicate when the relation between the number of calls waiting and the operators positions in service reaches a plurality of predetermined ratios.

5. In a telephone system, a plurality of operators positions, a plurality of link circuits having access to said positions, means to seize said link circuits, a calls waiting signal responsive to a given potential, means to reduce the potential connected to said signal as each of said positions is occupied, and means to increase the potential connected to said signal as each of said link circuits is seized.

6. In a telephone system, a plurality of operators positions, a plurality of link circuits having access to said positions, means to seize said link circuits, a calls waiting signal variably responsive to a plurality of given potentials, means to reduce the potential connected to said signal as each of said positions is occupied, means to increase the potential connected to said signal as each of said link circuits is seized, and means to indicate at each of said operators positions the response of said calls waiting signal to each of said potentials.

7. In a telephone system, a plurality of operators positions, a plurality of link circuits having access to said positions, means to seize said link circuits, a calls waiting signal circuit, means connected to a point in said circuit to display a signal at a given potential on said point, means to connect battery through parallel resistances to said point as each of said positions is occupied, and means to connect ground through parallel resistances to said point as each of said link circuits is seized.

CHARLES GIDEON MILLER. 

